<meta charset="utf-8">
(#) Application uses unsafe cipher modes or paddings with cryptographic algorithms

!!! WARNING: Application uses unsafe cipher modes or paddings with cryptographic algorithms
   This is a warning.

Id
:   `UnsafeCryptoAlgorithmUsage`
Summary
:   Application uses unsafe cipher modes or paddings with cryptographic algorithms
Severity
:   Warning
Category
:   Security
Platform
:   Any
Vendor
:   Google - Android 3P Vulnerability Research
Contact
:   https://github.com/google/android-security-lints
Feedback
:   https://github.com/google/android-security-lints/issues
Min
:   Lint 4.1
Compiled
:   Lint 8.0 and 8.1
Artifact
:   [com.android.security.lint:lint](com_android_security_lint_lint.md.html)
Since
:   1.0.1
Affects
:   Kotlin and Java files
Editing
:   This check runs on the fly in the IDE editor
See
:   https://goo.gle/UnsafeCryptoAlgorithmUsage
Implementation
:   [Source Code](https://github.com/google/android-security-lints/tree/main/checks/src/main/java/com/example/lint/checks/BadCryptographyUsageDetector.kt)
Tests
:   [Source Code](https://github.com/google/android-security-lints/tree/main/checks/src/test/java/com/example/lint/checks/BadCryptographyUsageDetectorTest.kt)
Copyright Year
:   2023

Using unsafe cipher modes or paddings with safe cryptographic algorithms
is insecure, and makes the code vulnerable to issues like padding oracle
attacks.

!!! Tip
   This lint check has an associated quickfix available in the IDE.

(##) Example

Here is an example of lint warnings produced by this check:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text
src/fake/pkg/TestBadCryptoDetector.kt:11:Error: Using insecure modes and
paddings with cryptographic algorithms is unsafe and vulnerable to
attacks [UnsafeCryptoAlgorithmUsage]
    Cipher.getInstance(algo + "/" + mode + "/" + padding)
    -----------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here is the source file referenced above:

`src/fake/pkg/TestBadCryptoDetector.kt`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~kotlin linenumbers
package fake.pkg

import javax.crypto.Cipher

class TestBadCryptoDetector {
    private fun foo() {
        val algo = "RSA"
        val mode = "CBC"
        val padding = "NoPadding"
        // There are problems with variables not being recognized with a string template
        Cipher.getInstance(algo + "/" + mode + "/" + padding)
    }
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can also visit the
[source code](https://github.com/google/android-security-lints/tree/main/checks/src/test/java/com/example/lint/checks/BadCryptographyUsageDetectorTest.kt)
for the unit tests for this check to see additional scenarios.

The above example was automatically extracted from the first unit test
found for this lint check, `BadCryptographyUsageDetector.testWhenUnsafeAlgoUsageCbcNoPadding_showsErrorAndQuickFix`.
To report a problem with this extracted sample, visit
https://github.com/google/android-security-lints/issues.

(##) Including

!!!
   This is not a built-in check. To include it, add the below dependency
   to your project. This lint check is included in the lint documentation,
   but the Android team may or may not agree with its recommendations.

```
// build.gradle.kts
lintChecks("com.android.security.lint:lint:1.0.3")

// build.gradle
lintChecks 'com.android.security.lint:lint:1.0.3'

// build.gradle.kts with version catalogs:
lintChecks(libs.com.android.security.lint.lint)

# libs.versions.toml
[versions]
com-android-security-lint-lint = "1.0.3"
[libraries]
# For clarity and text wrapping purposes the following declaration is
# shown split up across lines, but in TOML it needs to be on a single
# line (see https://github.com/toml-lang/toml/issues/516) so adjust
# when pasting into libs.versions.toml:
com-android-security-lint-lint = {
    module = "com.android.security.lint:lint",
    version.ref = "com-android-security-lint-lint"
}
```

1.0.3 is the version this documentation was generated from;
there may be newer versions available.

[Additional details about com.android.security.lint:lint](com_android_security_lint_lint.md.html).
(##) Suppressing

You can suppress false positives using one of the following mechanisms:

* Using a suppression annotation like this on the enclosing
  element:

  ```kt
  // Kotlin
  @Suppress("UnsafeCryptoAlgorithmUsage")
  fun method() {
     getInstance(...)
  }
  ```

  or

  ```java
  // Java
  @SuppressWarnings("UnsafeCryptoAlgorithmUsage")
  void method() {
     getInstance(...);
  }
  ```

* Using a suppression comment like this on the line above:

  ```kt
  //noinspection UnsafeCryptoAlgorithmUsage
  problematicStatement()
  ```

* Using a special `lint.xml` file in the source tree which turns off
  the check in that folder and any sub folder. A simple file might look
  like this:
  ```xml
  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;lint&gt;
      &lt;issue id="UnsafeCryptoAlgorithmUsage" severity="ignore" /&gt;
  &lt;/lint&gt;
  ```
  Instead of `ignore` you can also change the severity here, for
  example from `error` to `warning`. You can find additional
  documentation on how to filter issues by path, regular expression and
  so on
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html).

* In Gradle projects, using the DSL syntax to configure lint. For
  example, you can use something like
  ```gradle
  lintOptions {
      disable 'UnsafeCryptoAlgorithmUsage'
  }
  ```
  In Android projects this should be nested inside an `android { }`
  block.

* For manual invocations of `lint`, using the `--ignore` flag:
  ```
  $ lint --ignore UnsafeCryptoAlgorithmUsage ...`
  ```

* Last, but not least, using baselines, as discussed
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).

<!-- Markdeep: --><style class="fallback">body{visibility:hidden;white-space:pre;font-family:monospace}</style><script src="markdeep.min.js" charset="utf-8"></script><script src="https://morgan3d.github.io/markdeep/latest/markdeep.min.js" charset="utf-8"></script><script>window.alreadyProcessedMarkdeep||(document.body.style.visibility="visible")</script>